Statistical and numerical analysis on characteristics and influence factors of construction cracks of large-diameter underwater shield tunnel: a case study

Tunnel excavation is prone to segment cracks, which may lead serious safety accidents. This work aims investigate the type, location and occurrence time of cracks in a large-diameter underwater shield tunnel also ascertain causes cracks. The correlations between crack characteristics tunneling parameters were analyzed. effect jack deflection poor assembly on investigated using refined finite element model two consecutive rings with consideration clearance constraint machine. results confirmed that 93% formed current ring last jacking stage. Positive induced by occurred during stage, while lengths proportional boring machine segments, remained constant subsequent construction process. caused quality arose next stages. Furthermore, generated stage would propagate length, number influenced clearance. inverted V-shape longitudinal joints more than any other defects. finding this study conclusions are expected contribute reduction at tunnels eccentricity force transfer platforms.